Manufacture of aromatic alcohols



Patented Jan. 30, 1934 UNITED STATES MANUFACTURE OF AROMATIC ALCOHOLSLudwig Valik and Irene Valik, New York, N. Y.

No Drawing. Application March 20, 1933 Serial No. 661,844

13 Claims.

This invention relates to improvements in the manufacture of higheralcohols, and more particularly to such aromatic alcohols as thephenylethylalcohols, the tolylethylalcohols, the xylylethylalcohols, thephenyl propylalcohols, the

tolylpropylalcohols, the xylylpropylalcohols, hydratropic alcohols,methylbenzyl carbinol and homologues' thereof. This application is acontinuation in part of our application Ser. No. 614,840, filed June 1,1932.

An object of this invention is to produce a1- cohols such as abovereferred to by reacting on aromatic hydrocarbons such as'benzene,toluene, or xylene with an oxide such as ethylenoxide or the variouspropylenoxides in the presence of an acid condensing agent.

Another object of this invention is to so control the temperature rangesof operation that a maximum quantity of the alcohol will be produced.

Another object of the invention is to reduce the production of sideproducts such as dibenzyl and chlorhydrins, which have heretofore beenformed in objectionable quantity in reactions of this type and which arediflicult of removal from the alcohol, and if not removed, impair itsodor.

With these and other objects in view, the invention consists in thedisclosures to be hereinafter set forth and claimed, with theunderstand- 30 ing that the several necessary elements comprising ourinvention may be varied in proportions and arrangement, withoutdeparting from the spirit and scope of the appended claims.

It is well known that in accordance with the Friedel-Crafts reaction,aliphatic halogen compounds, in the presence of an acid condensing agentsuch as anhydrous aluminum chloride, react with aromatic hydrocarbons toform condensation products as the result of the elimination of ahydrogen halide. Thus, a mixture of benzene, aluminum chloride andmethylchloride react to form toluene and hydrogen chloride. But astoluene reacts under the same conditions with methylchloride to formxylene, and the lat- 45 ter to form trimethylbenzene, it is evident thatunder the hitherto known conditions of operation for Friedel-Craitssynthesis, a pure compound could not be obtained.

Furthermore, it is known that the Friedel- 50 Crafts synthesis may beused for the preparation of dibenzyl from benzene, aluminum chloride,ethylenoxide, and hydrochloric acid. However,

' this process, conducted under conditions known in the art, has notproduced more than a negli- 55 gible percentage of phenylethyl alcohol(CeHaCHaCHzOH) or similar aromatic alcohols.

We have determined, through experimental research. that the aromaticalcohol yield can be materially increased and the dibenzyl yield de- 60creased to substantially 1% of the total reaction mass, i. e., thepreviously obtained by-product alcohol can be shifted to the mainproduct, and the dibenzyl formerly obtained as the main product to aby-product, if proper conditions attend the reaction.

We have discovered that the excessive formation of dibenzyl,chlorhydrins, etc., can be prevented if the reaction with the liquidbenzene and the condensing agent is conducted with a preferably gaseousalkylene oxide such as ethyleneoxide, propylene oxide, etc., (that is,at a temperature above the boiling point of 15 for ethylene oxide, andabove 35C. for propylene oxide) mixed with gas inert to the reaction,

such as air. By this process using inert gas, the side reactions of thealcohol and the benzene to form dibenzyl, and of the ethylene oxide andnascent HCl to form chlorhydrins are largely inhibited. The inert gasfacilitates heat control, and also by reducing the nascent HClconcentration, reduces its detrimental effects. Thus, the yield ofalcohol of higher initial purity than has heretofore been obtained isincreased by onehalf or more, without dilution of the reacting liquid byliquid solvents or diluents. While we prefer to use a temperature atwhich the alkylene oxide is gaseous, we do not so restrict ourselves, aswe obtain increased yields and less side reactions at from -20 C. up, byusing inert as.

We have further discovered that a further increase up to 10% in theyield can be had by control 01' the exothermic reaction temperaturethrough the use of lumps of aluminum chloride or other acid condensingagent (from about the size of a hazel nut to a large walnut) instead ofpowder or granulated size as heretofore proposed.

It the evolved HCl gas is neutralized as formed,

as by addition of aliphatic or aromatic amines.

ammonia, or other neutralizer, the yield is i'urther increased.

Summarizing, we have first made a substantial gain over the prior art byusing inert gas, and can increase this gain up to 10% by using lumpcondensing agent, and further increase the yield by using a neutralizer.

Example 1 In a suitable container in which there has been placed 500grams of lump anhydrous A1013, there is added 800 grams of benzene understirring, 180 grams ethyleneoxide in gaseous form and an equal amount ofair are passed through the mixture at 45-55 C. until only a small amountof A101: has been left. The reaction container is constantly externallycooled with circulating water to maintain the desired temperature. Thetemperature is kept preferably within the range of about substantially45 C.

to about substantially 55 C. but as hereafter seen can range from -20 C.upwards. The reaction product obtained is treated in the usual way withice, separated and vacuum distilled. In this reaction about 173 gramsphenylethylalcohol and only 2 grams dibenzyl were formed.

Emample 2 To 800 grams of toluene are added 500 grams of lump anhydrousA1C13 through which is passed 180 grams of ethyleneoxide, preferablymixed with an equal amount of air or other inert gas with thetemperature maintained by cooling at between 45 and 55 C., until thealuminum chloride was practically used up. This gave a yield of 200grams tolyl ethyl alcohol with only 2 grams of ditolyl and a negligibleamount of chlorhydrin.

with the exception that during the reaction period, triethanolamine wasintroduced slowly into the reaction container for the purpose ofpreventing the formation of substantial quantities ofethylenechlorhydrin. By means of this alteration, a substantialimprovement in the aromatic alcohol yield was accomplished.

Similar conditions can be used for the preparation of other aromaticalcohols such as tolylethylalcohol from toluene and ethylene oxide,,xylylethylalcohol from xylene and ethylene oxide, phenylpropylalcoholand isomers from benzene and propylene oxide, tolylpropylalcohol andisomers from toluene and propylene oxide, and xylylpropylalcohol andisomers from xylene and propylene oxide.

For comparative purposes other runs have been made as follows, usinggranular aluminum chloride without a neutralizer:

At temperatures as low as 20 C. where the aromatic hydrocarbon is solidor viscous, a solvent such as petroleum ether is used, and the processcarried on with inert gas as above described, with equally good results.

By using the lump aluminum chloride as hereinbefore mentioned, the aboveyields on commercial scale are about 10% higher, and by using aneutralizing agent as previously mentioned, the above yields furtherincrease.

tially 55 C.

In any case the inert gas can be fed in separately during the reaction.

While we have above stated particular materials, conditions,proportions, and temperatures which have given the results stated, we donot restrict ourselves thereto except as required by the scope of theappended claims, as we consider that we have discovered a type reactionapplicable to a wide variety of Friedel-Crafts reactions, and desire toclaim same accordingly. In using the lump condensing agent, or aneutralizer, we do not restrict our claims to such use in connectionwith an inert gaseous mixture, but prefer to use all three incombination, and do not exclude the use of liquid organic solvents ordiluents.

The invention claimed is:

l. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic loydrocarbon with a gaseous mixture of alkyleneoxide and inert gas in the presence of an acid condensing agent.

2. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hydrocarbon with a gaseous mixture of an alkyleneoxide and an inert gas in the presence of an acid condensing agent and aneutralizing agent.

3. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hydrocarbon with ethyleneoxide in the presence 1.05of an acid condensing agent and neutralizing the formed hydrogenchloridein status nascens with an aliphatic amine.

4. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hydrocarbon with propyleneoxide in the presence ofan acid condensing agent and neutralizing the formed hyydrogenchloridein status nascens with an aliphatic amine.

5. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hydrocarbon with an alkylene oxide in the presenceof an acid condensing agent and neutralizing the formed hydrogenchloridein status nascens with an aromatic amine.

6. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hydrocarbon with an oxide of the ethylene seriesand an inert gas in the presence of an acid condensing agent at atemperature of from substantially 20 C. to substantially 55 C.

7. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hydrocarbon with a gaseous mixture of an oxide ofthe ethylene series and an inert gas in the presence of an acidcondensing agent at a temperature of from substantially 20 C tosubstantially 55 C.

8. A process for the manufacture of aromatic alcohols'comprisingreacting an aromatic hydrocarbon with a gaseous mixture of an oxide ofthe ethylene series and an inert gas in the presence of an acidcondensing agent at a temperature of from substantially 40 C. tosubstan- 9. A process for the manufacture of aromatic alcoholscomprising reacting an aromatic hydrocarbon with a gaseous mixture of anoxide of the ethylene series and an inert gas in the presence of an acidcondensing agent at a temperature of from substantially 20 C. tosubstantially 55 C., and neutralizing the acid reaction productasformed.

10. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hycirocarbon with a gaseous mixture of an oxide ofthe ethylene series and an inert gas in the alcohols comprising reactingan aromatic hydro= carbon with a gaseous mixture of approximately equalparts of alkylene oxide and inert gas in the presence of an acidcondensing agent.

13. A process for the manufacture of aromatic alcohols comprisingreacting an aromatic hydrocarbon with an alkylene' oxide in the presenceof an acid condensing agent, and passing through the reaction mixture aninert gas during substantially the entire reaction period.

LUDWIG V. IRENE V.

